Gas turbines include a compressor section that compresses air and feeds the compressed air to a combustor through a primary flowpath. Compressed air is mixed with fuel in the combustor and ignited, creating combustion gasses. The combustion gasses are expelled from the combustor through a turbine section, along the primary flowpath. As the combustion gasses pass through the turbine section, each stage of the turbine section is driven to rotate by the combustion gasses. Each stage is connected to a central shaft, and the rotation of the turbine stage is transferred to the shaft, thereby driving the shaft to rotate. In some implementations, such as a geared turbofan (GTF) engine, the rotation of the shaft drives a fan. In other gas turbine implementations, such as a land based turbine, the rotation of the shaft is output to an electrical generator, or another system requiring a rotational input.
To facilitate turbine operation, gas turbines include one or more turbine stages, with each stage having multiple blades arranged circumferentially in the flowpath at a single axial position. Each blade is paired with a corresponding vane. Due to the extreme temperatures of the combustion gasses, it is common practice to cool the blades and vanes to improve their ability to endure extended exposure to the hot combustion gasses. In some examples, relatively cool pressurized air is provided from elsewhere in the engine to the blades and vanes and operates as a coolant. In such an example, the blades are referred to as film cooled articles.